U.S. patent application number 11/077180 was filed with the patent office on 2005-09-15 for method for manufacturing wide mouth barrels of thermoplastic materials.
Invention is credited to Schutz, Udo.
Application Number | 20050200053 11/077180 |
Document ID | / |
Family ID | 34830759 |
Filed Date | 2005-09-15 |
United States Patent
Application |
20050200053 |
Kind Code |
A1 |
Schutz, Udo |
September 15, 2005 |
Method for manufacturing wide mouth barrels of thermoplastic
materials
Abstract
A wide mouth plastic barrel with a removable lid and a clamping
ring closure is manufactured by extruding a plastic tube into a
blow mold and by producing a closed preform. The preform is
finish-blown to a barrel body, wherein the blowing air for
finish-blowing a barrel body with a closed lid is introduced
through a blow nozzle inserted into an intermediate ring of the
barrel body and the blowing air for finish-blowing a barrel body
with a bung lid is introduced through a bung hole by a blow nozzle
and optionally through a blow nozzle in the intermediate ring.
After removal from the blow mold, the lid is separated from the
barrel body by cutting out the intermediate ring. A seal is
inserted into the barrel lid, and the barrel lid is fastened by the
clamping ring on a projection of the basic barrel member.
Inventors: |
Schutz, Udo;
(Selters/Westerwald, DE) |
Correspondence
Address: |
Friedrich Kueffner
Suite 910
317 Madison Avenue
New York
NY
10017
US
|
Family ID: |
34830759 |
Appl. No.: |
11/077180 |
Filed: |
March 10, 2005 |
Current U.S.
Class: |
264/540 |
Current CPC
Class: |
B29C 49/04 20130101;
B65D 45/32 20130101; B29C 49/4278 20130101; B29K 2305/00 20130101;
B29C 49/60 20130101; B29L 2009/00 20130101; B29C 49/20 20130101;
B29L 2031/7126 20130101; B65D 11/08 20130101; B29L 2031/565
20130101; B29C 2791/001 20130101; B29K 2995/0005 20130101; B29C
2049/2082 20130101; B29L 2031/7154 20130101 |
Class at
Publication: |
264/540 |
International
Class: |
B29C 049/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 11, 2004 |
DE |
10 2004 011 915.5 |
Jan 13, 2005 |
DE |
10 2005 001 649.9 |
Jan 31, 2005 |
DE |
10 2005 004 548.0 |
Claims
What is claimed is:
1. A method for manufacturing wide mouth barrels from thermoplastic
material, wherein the wide mouth barrels have a removable lid and a
clamping ring closure, the method comprising the steps of:
extruding a single-layer or multi-layer plastic tube into a blow
mold and producing a closed preform; finish-blowing the closed
preform to a barrel body having a basic barrel member, a bottom
with or without support ring, a barrel lid selected from the group
consisting of a closed lid or a bung lid, a projection on the basic
barrel member for attaching the barrel lid by means of a clamping
ring closure, wherein the projection is formed on the basic barrel
member at a level of a barrel opening rim or at a spacing below the
barrel opening rim of the wide mouth barrel, and an intermediate
ring between the projection and the barrel lid or the barrel
opening rim and the barrel lid; introducing blowing air for
finish-blowing the closed preform to a barrel body having a closed
lid through at least one injection blow nozzle inserted into the
intermediate ring and introducing the blowing air for
finish-blowing the closed preform to a barrel body with a bung lid
through at least one of a bung hole of at least one bung of the
bung lid by a blow nozzle and of at least one blow nozzle
introduced into the intermediate ring; after cooling of the barrel
body in the blow mold and removal of the barrel body from the blow
mold, separating the basic barrel member and the barrel lid from
one another by cutting out the intermediate ring from the barrel
body; inserting a seal into a sealing seat of the lid; and
fastening the lid by the clamping ring on the projection of the
basic barrel member.
2. The method according to claim 1, wherein, in the step of
extruding, a multi-layer tube of a non-conducting basic material is
coextruded together with at least one section arranged on a
circumference of the tube, wherein the section is a contact strip
of an electrically conducting plastic material, wherein the preform
is finish-blown to an electrically grounded barrel body with at
least one electrically conducting contact strip integrated into the
barrel lid, the intermediate ring, the basic barrel member, and the
barrel bottom, wherein the contact strip provides an electrical
connection between the inner surface and the outer surface of the
barrel body and has a thickness that matches a wall thickness of
the barrel body.
3. The method according to claim 2, wherein, in the step of
extruding, the multi-layer tube is extruded continuously or
discontinuously and is split at least at one location on the
circumference to form a gap and the electrically conducting plastic
material is injected into the gap and fuses homogeneously to the
non-conducting basic material of the tube to form the contact
strip.
4. The method according to claim 3, wherein the tube comprises an
inner layer and a conducting or permanently antistatic outer
layer.
5. The method according to claim 3, wherein the tube comprises an
inner layer, a central layer, and a conducting or permanently
antistatic outer layer.
6. The method according to claim 5, wherein the tube further
comprises a barrier layer arranged between the inner layer and the
central layer, wherein the barrier layer is embedded in two bonding
layers.
7. The method according to claim 1, further comprising, after the
step of finish-blowing, the step of introducing flushing air into
the barrel body through at least one blow nozzle that is inserted
into the intermediate ring.
8. The method according to claim 1, further comprising, after the
step of separating, the steps of exposing edges of cut produced on
the barrel lid and the basic barrel member by cutting out the
intermediate ring to hot air for removing burrs and subsequently
passing the barrel lid and the basic barrel member through a
cooling stretch.
9. The method according to claim 1, wherein, in the step of
finish-blowing, the barrel lid is formed with a downwardly open
U-shaped outer rim providing the sealing seat for receiving the
seal, wherein the outer ring with the sealing seat is pressed by
oppositely moving mold slides and cooling of the outer rim inwardly
and outwardly by the mold slides.
10. The method according to claim 9, wherein, in the step of
finish-blowing, a circumferential reinforcement bead for
reinforcing the barrel lid is formed between an engagement groove
adjoining the outer rim and provided for a barrel gripping device
and an annular stay formed below the engagement groove.
11. The method according to claim 1, wherein, in the step of
finish-blowing, the barrel lid is formed to have a lid bottom
surrounded by an outer rim and an inner rim that define a
downwardly open annular space provided with the sealing seat for
receiving the seal, wherein the barrel lid attached to the basic
barrel member surrounds with the outer rim a barrel neck and with
the inner rim, projecting past the lid bottom arranged below a
barrel opening rim of a barrel opening of the basic barrel member,
is immersed into the neck, wherein the barrel lid is fastened to
the basic barrel member by the clamping ring that engages the
projection formed below the opening rim and an annular flange of
the outer rim, wherein the outer rim and the inner rim are pressed
by oppositely moving mold slides and cooled inwardly and outwardly
by the mold slides.
12. The method according to claim 11, wherein in a corner area
between an underside of the lid bottom and the inner rim a
circumferential reinforcement bead is formed.
13. The method according to claim 12, wherein at a lower end of the
inner rim a conical reinforcement ring is formed.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a method for manufacturing wide
mouth barrels having a removable lid from thermoplastic
material.
[0003] 2. Description of the Related Art
[0004] For manufacturing wide mouth barrels of thermoplastic
material having a removable lid and a clamping ring as closure
means as disclosed in EP 0 781 234 B1, an extrusion blowmolding
method is used wherein in the first method step a plastic tube is
extruded from a tube-forming extrusion die head and in a second
method step the tube is pre-blown to a preform in a two-part blow
mold; the preform is subsequently finish-blown to a closed barrel
body that solidifies by contact with the cooled shaping walls of
the blow mold. Subsequently, for producing the barrel opening, the
top wall of the barrel body is cut out of the barrel body by a
cutting tool that performs a cut concentrical to the longitudinal
axis of the barrel body. The closure lids of the wide mouth barrels
are produced by an injection molding device. The manufacture of the
wide mouth lid barrels requires a blow molding device and an
injection molding device; this requires high installation
costs.
SUMMARY OF THE INVENTION
[0005] It is an object of the present invention to provide a
method, based on the aforementioned extrusion blowmolding method,
for manufacturing wide mouth barrels which method eliminates
injection molding of the lids by an injection molding device.
Moreover, the new method is to be developed further with regard to
manufacturing electrically grounded wide mouth barrels of
thermoplastic material.
[0006] In accordance with the present invention, this is achieved
in connection with a method of the aforementioned kind, wherein a
single-layer or multi-layer plastic tube is extruded into a blow
mold and is blown to a barrel body, in that a barrel body is
blowmolded that has a basic barrel member, a bottom with or without
support ring, a projection on the basic barrel member for attaching
a lid by means of a clamping ring closure, wherein the projection
is formed on the basic barrel member at the level of the barrel
opening rim or at a spacing below the barrel opening rim of the
wide mouth barrel to be produced, a closed lid or a bung lid, as
well as an intermediate ring between the projection and the barrel
lid or the barrel opening rim and the barrel lid, wherein the
blowing air for finish-blowing a closed preform to a barrel body
having a closed lid is introduced through at least one injection
blow nozzle inserted into the intermediate ring and the blowing air
for finish-blowing a closed preform to a barrel body with a bung
lid is introduced through the bung hole of at least one bung of the
bung lid by means of a blow nozzle and/or through at least one blow
nozzle introduced into the intermediate ring, and wherein, after
cooling of the barrel body in the blow mold and removal of the
barrel body from the blow mold, the basic barrel member and the lid
are separated from one another by cutting out the intermediate ring
from the barrel body and, after insertion of a sealing ring into a
sealing seat of the lid, the lid is fastened by means of a clamping
ring on the projection of the basic barrel member.
[0007] This object is further solved by coextruding a multi-layer
tube of a non-conducting basic material with at least one section
arranged on the circumference, in particular a contact strip of an
electrically conducting plastic material, as well as pre-blowing of
the tube to a pre-from and finish-blowing of the pre-from to an
electrically grounded barrel body with at least one electrically
conducting contact strip integrated into the barrel lid, the
intermediate ring, the basic barrel member, and the barrel bottom,
wherein the contact strip provides an electrical connection between
the inner surface and the outer surface of the barrel body and has
a thickness that matches the wall thickness of the barrel body.
[0008] The dependent claims define further advantageous
modifications.
[0009] The method according to the invention for manufacturing wide
mouth barrels of thermoplastic material is based on the extrusion
blowmolding method disclosed in EP 0 781 234 B1 for manufacturing
wide mouth barrels; however, the method according to the invention
eliminates the need for injection molding the barrel lid by means
of an injection molding device and enables the manufacture of wide
mouth plastic barrels with a comprehensive electrical grounding
with which the electrical charges that occur within the liquid
material contained in the barrels and on the inner surface of the
barrels and the electrical charges that are generated by friction
on the outer surface of the barrel are discharged into the ground
by means of the electrically conducting contact strips, integrated
in the barrel body, the bottom, and the lid of the barrels, and by
means of the conducting or permanent antistatic outer layer of the
barrels. The electrical grounding of the outer surface of the
barrels and of the interior of the barrels as well as of the
liquids transported or stored therein and the bulk materials
transported and stored therein enables the use of the barrels
manufactured according to the present invention as containers for
hazardous materials for combustible liquids, emulsions, solvents,
paints, and enamel paints, having a flash point of <61.degree.
C. as well as for easily inflammable bulk materials and the use of
the barrels in work areas in which an explosive atmosphere can be
generated by gases, vapors or mist.
BRIEF DESCRIPTION OF THE DRAWING
[0010] In the drawing:
[0011] FIG. 1 shows a longitudinal section of a barrel body with
support ring and closed lid that has been removed from a blow
molding device after blowmolding and cooling;
[0012] FIG. 2 shows a longitudinal illustration of the basic barrel
member and the barrel lid after having cut the intermediate ring,
required for introducing the injection blow nozzle for the
blowmolding process, from the barrel body according to FIG. 1;
[0013] FIG. 3 is a side view of the assembled wide mouth barrel
with support ring and closed lid;
[0014] FIG. 4 is a detail illustration of the lid area of the wide
mouth barrel according to FIG. 3;
[0015] FIG. 5 shows a detail cross-section of the barrel wall of
the wide mouth barrel according to FIG. 3 having a three-layer
configuration;
[0016] FIG. 6 shows a wall section according to FIG. 5 of a wide
mouth barrel having a six-layer configuration;
[0017] FIGS. 7a and 7b show schematically in a detail view a closed
and an open blow mold, respectively, with a blowmolded barrel
body;
[0018] FIG. 8 is a longitudinal section view of a barrel body,
removed from a blow mold, provided with support ring and bung lid
as well as an intermediate ring for introducing the blow
nozzle;
[0019] FIG. 9 is a longitudinal section of a barrel body, removed
from the blow mold, with support ring and bung lid as well as a
narrow intermediate ring wherein the barrel body has been
blow-molded by means of a blow nozzle introduced into the bung hole
of an airing and venting bung;
[0020] FIG. 10 is a perspective illustration of an assembled wide
mouth barrel in a further embodiment with a closed lid; and
[0021] FIG. 11 is a detail view of the lid area of a wide mouth
barrel according to FIG. 10.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] When employing extrusion blowmolding for manufacturing wide
mouth barrels of a thermoplastic material, in the first method step
a multi-layer plastic tube of a non-conducting basic material is
extruded through the extrusion die head of a blow molding device;
the tube is in particular a three-layer tube comprised of an inner
layer, a central layer, a conducting or permanently antistatic
outer layer as well as at least one contact strip that is arranged
on the circumference and is comprised of an electrically conducting
plastic material. The extruded multi-layer plastic tube, after
closing the upper tube end by means of a closure tool, is pre-blown
by blowing air that is introduced through a blow nozzle inserted
into the lower end of the tube.
[0023] There is also the possibility of pre-blowing the extruded
tube to a preform by closing the lower tube end by means of blowing
air that is supplied through a nozzle arranged in the extrusion die
head.
[0024] Subsequently, after squeezing the lower end of the pre-from
by means of a closure unit and closing the two mold halves of the
divided blow mold 1 (illustrated in FIGS. 7a and 7b), in the second
method step the preform is then blown to a barrel body 2
illustrated in FIG. 1 that comprises a basic barrel member 3, a
bottom 4 with a support ring 5, a projection 6 on the basic barrel
member 3 at the level of the barrel opening rim 7 of the wide mouth
barrel 8 to be produced, a closed lid 9, an intermediate ring 10
between the projection 6 and the barrel lid 9, as well as an
electrical contact strip 11 integrated into the lid 9, the
intermediate ring 10, the basic barrel member 3, and the bottom 4
of the barrel 4. The electrically conducting contact strip 10
provides an electrical connection between the inner surface 12 and
the outer surface 13 of the barrel body 2 and has a thickness that
matches the wall thickness of the barrel body 2. The blowing air is
supplied through one or several blow nozzles 14 that is/are
inserted into a section of the preform that is blowmolded to the
intermediate ring 10 of the barrel body 2.
[0025] Upon coextrusion of the multi-layer plastic tube into the
blow mold, the material tube that exits from the extrusion die head
continuously or discontinuously is split at least at one location
of its circumference and into the resulting gap an electrically
conducting plastic material is injected for forming a contact strip
that fuses homogeneously with the preform.
[0026] In the barrel embodiment according to FIGS. 1 through 4, the
barrel body 2 is blowmolded with a closed lid 9 that has a
downwardly open U-shaped outer rim 15 with a sealing seat 16 for
receiving a lid seal or gasket 17. Upon finish-blowing the barrel
body 2 in the blow mold 1 the lid rim 15 and the sealing seat 16
are pressed by two oppositely moving mold slides 18, 19 (FIG. 7a).
By pressing the lid rim, a shape-stable (dimensionally stable) lid
with a proper sealing seat without any disruptive bead in the area
of the mold division plane is blowmolded that does not require any
post processing.
[0027] Upon finish-blowing a barrel body 2 in the blow mold 1, a
circumferential reinforcement bead 20 for reinforcing the barrel
lid is formed on the transition section 21 between an engagement
groove 22 adjoining the outer rim 15 of the lid 4 and provided for
a barrel gripping or lifting device and an annular stay 23 formed
below the engagement groove 22.
[0028] After cooling the barrel body 2 with the closed lid 9 whose
U-shaped outer rim 15 is cooled by the mold slides 18, 19 from the
interior and exterior, the blow mold 1 is opened and the barrel
body 2 is removed from the blow mold (FIG. 7b).
[0029] Subsequently, in accordance with FIGS. 1, 2 and 7b, the
intermediate ring 10 is cut out from the barrel body 2 along the
designated separating lines 24, 25 by two cuts guided
perpendicularly to the longitudinal axis 26-26 of the barrel body
2, and the edges of cut 27, 28 of the basic barrel member 3 and of
the lid 3 are exposed to hot air for removing the burrs of the
cut.
[0030] Subsequently, the basic barrel member 3 and the lid 9 pass
through a cooling stretch.
[0031] At this point, a seal (sealing ring or gasket) 17 is
inserted into the sealing seat 16 of the lid 9 and, subsequently,
during final assembly of the wide mouth barrel 8, the lid 9 is
attached by means of a clamping ring 29 on the projection 6 of the
basic barrel member 3 (FIGS. 3 and 4).
[0032] FIG. 5 shows a three-layer configuration of basic barrel
member 3, bottom 4, and lid 9 of the wide mouth barrel 8 with an
inner layer 30, a central layer 31, and a conducting or permanently
antistatic outer layer 32 that contains, for example, a proportion
of conducting carbon black.
[0033] For manufacturing the central layer 31, a recycled granular
material or ground material of pure polyethylene and/or
polyethylene containing a conducting carbon black proportion is
used as a starting material; for the inner and the outer layers 30,
32 a virgin granular polyethylene material is used.
[0034] FIG. 6 shows a six-layer configuration of a wide mouth
barrel 8 with an inner layer 30 of pure polyethylene of
high-density (HDPE); a barrier layer 33 of polyamide (PA) or an
ethylene vinyl acetate copolymer (EVA) that is provided against
permeation of oxygen and hydrocarbons and is embedded in two
bonding layers 34, 35 of polyethylene of low density (LLDPE); a
central layer 31 of recycled granules or ground material of pure
polyethylene of high density and/or polyethylene of high density
containing a conducting carbon black proportion; and a conducting
or permanently antistatic outer layer 32 of polyethylene of high
density containing a conducting carbon black proportion.
[0035] At least one electrically conducting contact strip 11 of
polyethylene of high density with a conducting carbon black
proportion is integrated into the basic barrel member 3, the bottom
4, and the lid 9 of the wide mouth barrel 8; the contact strip 11
provides an electrical connection between the inner surface 12 and
the outer surface 13 of the wide mouth barrel 8 and has a thickness
matching the wall thickness 36 of the barrel. The electrically
conducting contact strip 11 extends parallel to the longitudinal
axis 26-26 of the barrel across the cylindrical basic barrel member
3 and radially across the bottom 4 and the closed lid 9 of the wide
mouth barrel 8.
[0036] The wide mouth barrel 8 is electrically grounded by means of
the electrically conducting contact strip 11 and the conducting or
permanently antistatic outer layer 32 so that electrical charges
that occur at the inner surface 12 of the barrel 8 and in the
filled-in liquid material or in the bulk material as well as on the
outer surface 13 of the barrel are discharged or dissipated into
the ground.
[0037] According to the disclosed method it is also possible to
produce a wide mouth barrel 8 without a support ring that is
provided instead with a rounded transition between the basic barrel
member 3 and the barrel bottom 4 (FIG. 10).
[0038] Moreover, there is the possibility of producing by means of
the described method wide mouth barrels with a bung lid 37 that has
a filling and removal bung 38 and an airing and venting bung 39
(FIGS. 8 and 9). When producing wide mouth barrels with a bung lid
37, the blowing air for finish-blowing the closed preform is
introduced through the bung hole 40 of one of the two bungs 38, 39
by means of a blow nozzle. Through the blow nozzle(s) 14 inserted
into the intermediate ring 10 of the barrel body flushing air can
be introduced into the finish-blown barrel body for cooling it in
the blow mold 1. When introducing flushing air through one or both
bungs 38, 39 of the bung lid 37 of the finish-blown barrel body 2,
the inserted blow nozzles in the intermediate ring 10 are no longer
required so that the intermediate ring can be designed to be
narrower (FIG. 9).
[0039] FIGS. 10 and 11 show a wide mouth barrel 8 produced by the
afore described method and having a closed lid or a bung lid 41
that has an outer rim 42 and an inner rim 43 with a downwardly open
annular space 44 with a sealing seat 16 for receiving a lid seal or
gasket 17. The lid 41 attached to the basic barrel member 3
surrounds with its outer rim 42 the barrel neck 45 and with its
inner rim 43 that projects past the lid bottom 46 arranged below
the opening rim 7 of the barrel is immersed in the neck 45. The lid
41 is fastened to the basic barrel member 3 by means of a clamping
ring 29 that engages a projection 47 formed below the opening rim 7
and an annular flange 48 of the outer rim 42 of the lid 41.
[0040] In the corner area between the underside 49 of the lid
bottom 46 and the inner rim 43 of the lid 41 a circumferential
reinforcement bead 50 is formed and at the lower end of the inner
rim 43 of the lid 41 a conical reinforcement ring 51 is
arranged.
[0041] The afore described method can be used for manufacturing
wide mouth barrels that are not electrically grounded in this case,
the plastic tube that is extruded in the blow mold and is of a
single-layer or multi-layer configuration is not provided with an
electrically conducting plastic material.
[0042] While specific embodiments of the invention have been shown
and described in detail to illustrate the inventive principles, it
will be understood that the invention may be embodied otherwise
without departing from such principles.
* * * * *